“The accumulation technique hadn’t been invented yet and it got invented during this session. I was asking the engineer, describing to him the kind of sound I had worked with in Mescaline Mix. I wanted this kind of long, repeated loop and I said, ‘can you create something like that?’ He got it by stringing the tape between two tape recorders and feeding the signal from the second machine back to the first to recycle along with the new incoming signals. By varying the intensity of the feedback you could form the sound either into a single image without any delay or increase the intensity until it became a dense chaotic kind of sound. I enjoy the interplay between the two extremes. This engineer was the first to create this technique that I know of, this began my obsession with time-lag accumulation feed-back. It took me quite a while before I could afford to buy two good tape recorders to run this process in my own studio.”
Terry Riley

Out of doing all that experimentation with sound I decided I wanted to do it with live musicians. To take repetition, take music fragments and make it live. Musicians would be able to play it and create this kind of abstract fabric of sound.
Terry Riley